From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xsvjN1D41zDrTD for ; Thu, 14 Sep 2017 07:21:11 +1000 (AEST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8DLKtRH016786 for ; Wed, 13 Sep 2017 17:21:09 -0400 Received: from e23smtp05.au.ibm.com (e23smtp05.au.ibm.com [202.81.31.147]) by mx0a-001b2d01.pphosted.com with ESMTP id 2cy9u7jeta-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 13 Sep 2017 17:21:09 -0400 Received: from localhost by e23smtp05.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 Sep 2017 07:21:07 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay07.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v8DLL4DU39714820 for ; Thu, 14 Sep 2017 07:21:04 +1000 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v8DLL53u026438 for ; Thu, 14 Sep 2017 07:21:06 +1000 From: "Naveen N. Rao" To: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, Ananth N Mavinakayanahalli , Masami Hiramatsu , Kamalesh Babulal Subject: [PATCH 5/5] powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() Date: Thu, 14 Sep 2017 02:50:36 +0530 In-Reply-To: <2bc413d679c563d3ee338c318066777318577ab2.1505336870.git.naveen.n.rao@linux.vnet.ibm.com> References: <2bc413d679c563d3ee338c318066777318577ab2.1505336870.git.naveen.n.rao@linux.vnet.ibm.com> In-Reply-To: <2bc413d679c563d3ee338c318066777318577ab2.1505336870.git.naveen.n.rao@linux.vnet.ibm.com> References: <2bc413d679c563d3ee338c318066777318577ab2.1505336870.git.naveen.n.rao@linux.vnet.ibm.com> Message-Id: <58db21d55022d7fb95468f3b8fd3dbffec36a113.1505336870.git.naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Fix a circa 2005 FIXME by implementing a check to ensure that we actually got into the jprobe break handler() due to the trap in jprobe_return(). Signed-off-by: Naveen N. Rao --- This is v2 of the patch posted previously (*) to change the WARN() to a pr_debug() as suggested by Masami. (*) https://patchwork.ozlabs.org/patch/762670/ - Naveen arch/powerpc/kernel/kprobes.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index db40b13fd3d1..5b26d5202273 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -648,24 +648,22 @@ NOKPROBE_SYMBOL(setjmp_pre_handler); void __used jprobe_return(void) { - asm volatile("trap" ::: "memory"); + asm volatile("jprobe_return_trap:\n" + "trap\n" + ::: "memory"); } NOKPROBE_SYMBOL(jprobe_return); -static void __used jprobe_return_end(void) -{ -} -NOKPROBE_SYMBOL(jprobe_return_end); - int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - /* - * FIXME - we should ideally be validating that we got here 'cos - * of the "trap" in jprobe_return() above, before restoring the - * saved regs... - */ + if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) { + pr_debug("longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n", + regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap")); + return 0; + } + memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); /* It's OK to start function graph tracing again */ unpause_graph_tracing(); -- 2.14.1